Digital Cameras - Canon PowerShot A100 Test Images
(Original test posting: 07/17/02)
| I've begun including links in our reviews to a Thumber-generated index page for our test shots. The Thumber data includes a host of information on the images, including shutter speed, ISO setting, compression setting, etc. Rather than clutter the page below with *all* that detail, I'm posting the Thumber index so only those interested in the information need wade through it! |
| Outdoor
Portrait:
The extreme tonal range of this image makes it a tough shot for many digicams, which is precisely why I set it up this way. The object is to hold highlight and shadow detail without producing a "flat" picture with muddy colors, and the A100 performed well. The shot at right was taken with a +0.3 EV exposure compensation adjustment, which keeps the highlights from losing detail, but leaves the midtones somewhat dark. Increasing the exposure compensation brightens midtones, but washes out color and produces very bright highlights. I chose the Auto white balance setting as the most accurate, though the Daylight setting produced similar results (just slightly warm). Skin tones look about right, though the blue flowers are dark and purplish (a common problem with this shot). Resolution is fairly high, and details are crisp and defined. Detail also looks good in the shadows, with low noise. To view the entire exposure series from zero to +0.7, see files A10OUTAP0.HTM
through A10OUTAP2.HTM on the thumbnail index page.
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Severe distortion from the fixed focal length lens, but great detail
and resolution. Results are similar to the wider shot above, but the A100's fixed focal
length lens distorts Marti's features in this closeup shot. The level
of fine detail in her face and hair is excellent, with sharp definition.
Detail is again strong in the shadow areas, with low noise. The main shot
was taken without an exposure compensation adjustment, which results in
slightly dark midtones, but preserves detail in the highlights.
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Good intensity with an exposure adjustment, good color, but a lot of color cast from the room lighting. The A100's flash was slightly dim at the camera's default
exposure setting, and a pinkish-orange cast from the household incandescent
lighting affected the color balance of the entire image. Boosting the
exposure compensation to +0.7 EV brightened
the image significantly, decreasing the orange cast and producing more
accurate color on Marti. (Adjusting the exposure to +1.0
EV was too bright.) I also shot with the camera's Slow Sync flash
mode, which allowed more ambient light into the image with a slightly
longer exposure time. While more light brightens the image, the orange
cast is stronger. Additionally, the longer exposure time results in a
slightly blurred image, from Marti's movement. The best results were again
achieved with a +0.7 EV exposure compensation
adjustment. (Click here for sample images at zero
and +1.0 EV.)
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This shot is always a very tough test of a camera's white balance capability, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting. The A100's Auto white balance setting had a hard time with the difficult lighting, producing a very warm color cast with a sepia tint. The Incandescent setting produced more accurate results, though still with a slightly warm cast. (I actually like a slightly warm tone on this shot, as it retains some of the mood of the original lighting. I might like just a bit less cast than shows here, but this is a very good handling of this subject, IMHO.) Overall color looks nearly right, though the white shirt has a greenish/yellow tint. Skin tones are pretty good, but the blue flowers are dark and purplish from the warm color balance, a common problem with this shot. The main shot has a +1.0 EV exposure compensation adjustment. To view an abbreviated exposure series (zero, +1.0, and +1.3 EV), see files A10INTP0.HTM, A10INTP3.HTM, and A10INTP4.HTM on the thumbnail index page. ISO Series:
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High resolution (for a 1.3 megapixel camera) with good detail, and accurate color. The A100's Auto white balance setting produced
the best color here, though the white value of the trim has a reddish
tint. Daylight white balance resulted in a warmer
shot, with a yellow cast. Resolution is high, with good definition in
the fine detail of the tree limbs above the roof and in the shrubbery
in front of the house. (Some foliage details appear to be defined more
by contrast, however.) Details are reasonably sharp throughout the frame,
though all four corners are soft.
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This image is shot at infinity to test far-field lens performance. NOTE that this image cannot be directly compared to the other "house" shot, which is a poster, shot in the studio. The rendering of detail in the poster will be very different than in this shot, and color values (and even the presence or absence of leaves on the trees!) will vary in this subject as the seasons progress. In general though, you can evaluate detail in the bricks, shingles and window detail, and in the tree branches against the sky. Compression artifacts are most likely to show in the trim along the edge of the roof, in the bricks, or in the relatively "flat" areas in the windows. This is my ultimate "resolution shot," given the infinite range of detail in a natural scene like this, and the A100 found plenty of detail but rendered it rather softly. (Do keep in mind though, that this is a 1.3 megapixel camera, which will naturally be softer than the two- and three-megapixel models seen elsewhere on this site.) Despite soft focus and slightly blurred details, resolution is high. The tree limbs above the roof and the shrubbery in front of the house show a lot of fine detail, though not well-defined. The distance from the subject makes it hard to determine how much detail the camera actually picks up in the white trim around the bay window, but it appears that the A100 captures most of the stronger details. (The harsh sunlight often tricks digicams here.) There's also a fair amount of detail in the brick pattern of the shadow area above the front porch, so the A100 seems to have good dynamic range. Color looks about right from the Auto white balance setting, though saturation is slightly weak in the red values. The table below shows a our standard resolution and quality series, followed by an ISO series. Resolution Series:
ISO Series:
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Lens Zoom Range Typical fixed focal length performance. I routinely shoot this series of images to show the field of view for each camera, with the lens at full wide angle, at maximum telephoto (none, in this case), and at full telephoto with the digital zoom enabled. The A100's lens is equivalent to a 39mm lens on a 35mm camera, which is a slight wide angle. Following are the results at both settings.
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Good color with Auto white balance, good detail as well. This shot is generally a tough test for digicams, as the abundance of
blue in the composition often tricks white balance systems into producing
a warm color balance. The A100's Auto white
balance performed well here, though the Daylight
setting responded with a warm color balance. Skin tones look good with
the Auto white balance, though just a hint warm, and the blue robe is
about right as well (though with a slight greenish tint). The blue robe
also has faint purple tints in the deep shadow areas, a common problem
among digicams with this shot. Resolution is pretty good for a 1.3 megapixel,
as the embroidery of the blue robe, the flower garland, and the beaded
necklaces all show strong detail.
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The A100 performed very well in the macro category, capturing a minimum
area of just 2.04 x 1.53 inches (51.7 x 38.8 millimeters). Detail is strong
in the coins, dollar bill, and brooch, with high resolution. Details are
just a hint soft, but still well-defined. Some corner softness is present
in all four corners, but the effect is slight. Color looks about right
with the Auto white balance, and exposure is good. The A100's flash
had trouble throttling down for the macro area, creating a hot spot in
the top left corner and dark shadows in the bottom of the frame.
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Accurate color, slightly weak saturation. Very good overall though. The Auto white balance setting produced nearly accurate color here, while the Daylight setting resulted in a warm cast. The large color blocks are about right, though saturation is just slightly weak. (Click here for sample images with the camera's Neutral and Vivid color settings.) Exposure is a hint bright, but the A100 captures the subtle tonal variations of the Q60 target well. The shadow area of the charcoal briquettes shows moderate detail, with low noise. Overall, a good job. ISO Series:
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Low-Light Tests Sensitive enough for average city night shots, and slightly darker situations. The A100 features automatic exposure control, but a range of ISO settings enhance its low-light shooting abilities. With the camera's sensitivity set to ISO 400, the A100 captured bright images at light levels as low as 1/4 foot-candle (2.7 lux), though image noise was high. At ISO 200, images were bright as low as 1/2 foot-candle (5.5 lux), with moderate noise. Set to ISO 64 and 100, the A100 captured bright images only as low as one foot-candle (11 lux), equivalent to typical city street lighting at night. Noise was low at the 64 and 100 ISO settings. The Auto white balance setting produced good color, though a slight warm cast appeared in the darker shots. The table below shows the best exposure we were able to obtain for each of a range of illumination levels, at each ISO setting. Images in this table (like all of our sample photos) are untouched, exactly as they came from the camera.
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| Flash Range Test
Slightly dim at all distances, but reasonably bright at 14 feet. The A100's flash was brightest at eight feet from the test target, and decreased slightly in brightness from nine feet on out to 14 feet. I'd rate its range at 9-10 feet. The flash was still effective at 14 feet, but the decreased brightness was accompanied by a warm cast. Below is our flash range series, with distances from eight to 14 feet from the target. (Images are slightly blurred due to the digital telephoto, which is the only "zoom" available on the A100.)
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ISO-12233 (WG-18) Resolution Test
The A100 performed about average on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 300 lines per picture height, but I found "strong detail" out to at least 600 lines. "Extinction" of the target patterns occurred at about 750 lines. Horizontal resolution is a good bit better than vertical. Optical distortion on the A100 is moderate, as I measured a 0.60 percent barrel distortion. Chromatic aberration is practically nonexistent, showing about one or two pixels of very light coloration on either side of the target lines. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.) The strongest optical distortion was some corner softness, most visible in the House shot. Resolution Series, Wide Angle
Sharpness Series
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Viewfinder Accuracy/Flash Uniformity A nearly accurate optical viewfinder and LCD monitor. The A100's optical viewfinder is only a little tight, measuring approximately 93 percent frame accuracy, good results for an optical viewfinder. Because the viewfinder eyepiece has a fair amount of extra space around all four sides (as you move your eye slightly you can see more image area), I found it best to frame the shot in the dead center of the view, which produced the most accurate results. The LCD monitor was slightly more accurate, as I measured about 97 percent frame accuracy. Given that I generally prefer LCD monitors to be as close to 100 percent accuracy as possible, the A100's LCD monitor performs well here (as does its optical viewfinder). Flash distribution is slightly uneven, with some falloff in the corners and at the edges of the frame.
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